<template>
	<view class="u-wrap">
		<view class="u-search-box">
			<view class="u-search-inner">
				<u-search placeholder="商品关键字" v-model="keyword"  @custom="toSearch" ></u-search>
			</view>
			
		</view>
		<!-- 选项卡开始 -->
		<u-tabs :list="list" :is-scroll="false" :current="current2" @change="change" active-color="#ff9900" class="tabs u-skeleton-rect"></u-tabs>
		<!-- 选择卡结束 -->
		<view class="u-menu-wrap">
			<scroll-view scroll-y scroll-with-animation class="u-tab-view menu-scroll-view" :scroll-top="scrollTop"
			 :scroll-into-view="itemId">
				<view v-for="(item,index) in tabbar.categories" :key="index" class="u-tab-item" :class="[current == index ? 'u-tab-item-active' : '']"
				 @tap.stop="swichMenu(index)">
					<text class="u-line-1">{{item.name}}</text>
				</view>
			</scroll-view>
		
			<scroll-view :scroll-top="scrollRightTop" scroll-y scroll-with-animation class="right-box" @scrolltolower="scrollEvent">
				
				<view class="page-view" >
					
					<view class="class-item" >
						<view class="u-body-item u-flex u-row-between u-p-b-0" v-for="(item1, index1) in cateList" :key="index1" @click="goTo(item1.id)">
							<image :src="item1.cover_url" mode="aspectFill"></image>
							<view class="title u-line-2">{{item1.title}}</view>
							<view class="price u-line-1">
								￥{{item1.price+'.00'}}
							<u-divider class="u-m-t-20">-</u-divider>
							</view>
							<view class="sales u-line-1">销量：{{item1.sales}}
							</view>
							
						</view>
					</view>
				</view>
			</scroll-view>
		</view>
	</view>
</template>
<script>
	
	export default {
		data() {
			return {
				scrollTop: 0, //tab标题的滚动条位置
				oldScrollTop: 0,
				current: 0, // 预设当前项的值
				menuHeight: 0, // 左边菜单的高度
				menuItemHeight: 0, // 左边菜单item的高度
				itemId: '', // 栏目右边scroll-view用于滚动的id
				tabbar: [],
				menuItemPos: [],
				arr: [],
				scrollRightTop: 0, // 右边栏目scroll-view的滚动条高度
				timer: null, // 定时器
				cateList:[],
				page:1,
				keyword: '',
				isLast:false, //最后一页
				list: [{
					name: '销量'
				}, {
					name: '价格'
				}, {
					name: '评论'
				}],
				current2: 0

			}
		},
		onLoad() {
			this.goodsres()
		},
		onReady() {
			this.getMenuItemTop()
		},
		methods: {
			//选项卡
			change(index) {
				this.current2 = index;
				this.cateList = []
				this.page = 1
				this.goodsres()
			},
			//商品列表AIP
			async goodsres(){
				const params = {
					page:this.page,
					title:this.keyword,
					// category_id:this.current
				}
				
				if(this.current2 == 0) params.sales = 1
				if(this.current2 == 1) params.price = 1
				if(this.current2 == 2) params.comments_count = 1
				//判断是否有分类ID
				if(this.current) params.category_id = this.current
				const res = await this.$u.api.goodsList(params)
				//console.log(res)
				this.tabbar = res
				this.cateList = [...this.cateList,...res.goods.data]
				this.isLast = res.goods.next_page_url ? false : true
			},
			//商品搜索
			toSearch(){	
				// console.log(this.keyword)
				this.cateList = []
				this.page =1 
				this.goodsres()
				setTimeout(()=>{
					this.keyword = ''
				},5000)
                
			},
			// 点击左边的栏目切换
			async swichMenu(index) {
				if (index == this.current) return;
				this.current = index;
				this.cateList = []
				this.page =1
				this.goodsres()
			},
			//右侧到底加载下一页
			scrollEvent(e){
				if(this.isLast) return
				//带上分页重新请求数据
				this.page = this.page + 1
				//this.$u.toast('加载中')
				uni.showToast({
					title:'加载中...',
					icon:'loading',
				})
				this.goodsres()
			},
			//跳转
			goTo(id){
				this.$u.route({
					type:'navigateTo',    //navigateTo 带反回,
					url:'/pages/cate/goodsdetail?id='+id
				})
			},
			
			
			// 获取一个目标元素的高度
			getElRect(elClass, dataVal) {
				new Promise((resolve, reject) => {
					const query = uni.createSelectorQuery().in(this);
					query.select('.' + elClass).fields({
						size: true
					}, res => {
						// 如果节点尚未生成，res值为null，循环调用执行
						if (!res) {
							setTimeout(() => {
								this.getElRect(elClass);
							}, 10);
							return;
						}
						this[dataVal] = res.height;
						resolve();
					}).exec();
				})
			},
			// 观测元素相交状态
			async observer() {
				this.tabbar.map((val, index) => {
					let observer = uni.createIntersectionObserver(this);
					// 检测右边scroll-view的id为itemxx的元素与right-box的相交状态
					// 如果跟.right-box底部相交，就动态设置左边栏目的活动状态
					observer.relativeTo('.right-box', {
						top: 0
					}).observe('#item' + index, res => {
						if (res.intersectionRatio > 0) {
							let id = res.id.substring(4);
							this.leftMenuStatus(id);
						}
					})
				})
			},
			// 设置左边菜单的滚动状态
			async leftMenuStatus(index) {
				this.current = index;
				// 如果为0，意味着尚未初始化
				if (this.menuHeight == 0 || this.menuItemHeight == 0) {
					await this.getElRect('menu-scroll-view', 'menuHeight');
					await this.getElRect('u-tab-item', 'menuItemHeight');
				}
				// 将菜单活动item垂直居中
				this.scrollTop = index * this.menuItemHeight + this.menuItemHeight / 2 - this.menuHeight / 2;
			},
			// 获取右边菜单每个item到顶部的距离
			getMenuItemTop() {
				new Promise(resolve => {
					let selectorQuery = uni.createSelectorQuery();
					selectorQuery.selectAll('.class-item').boundingClientRect((rects) => {
						// 如果节点尚未生成，rects值为[](因为用selectAll，所以返回的是数组)，循环调用执行
						if(!rects.length) {
							setTimeout(() => {
								this.getMenuItemTop();
							}, 10);
							return ;
						}
						rects.forEach((rect) => {
							// 这里减去rects[0].top，是因为第一项顶部可能不是贴到导航栏(比如有个搜索框的情况)
							this.arr.push(rect.top - rects[0].top);
							resolve();
						})
					}).exec()
				})
			},
			// 右边菜单滚动
			async rightScroll(e) {
				this.oldScrollTop = e.detail.scrollTop;
				if(this.arr.length == 0) {
					await this.getMenuItemTop();
				}
				if(this.timer) return ;
				if(!this.menuHeight) {
					await this.getElRect('menu-scroll-view', 'menuHeight');
				}
				setTimeout(() => { // 节流
					this.timer = null;
					// scrollHeight为右边菜单垂直中点位置
					let scrollHeight = e.detail.scrollTop + this.menuHeight / 2;
					for (let i = 0; i < this.arr.length; i++) {
						let height1 = this.arr[i];
						let height2 = this.arr[i + 1];
						// 如果不存在height2，意味着数据循环已经到了最后一个，设置左边菜单为最后一项即可
						if (!height2 || scrollHeight >= height1 && scrollHeight < height2) {
							this.leftMenuStatus(i);
							return ;
						}
					}
				}, 10)
			}
		}
	}
</script>

<style lang="scss" scoped>
	.u-wrap {
		height: calc(100vh);
		/* #ifdef H5 */
		height: calc(100vh - var(--window-top));
		/* #endif */
		display: flex;
		flex-direction: column;
	}
    .tabs{
    	position: sticky;
    	top: 0 !important;
		margin-left: 200rpx;
    	z-index: 999;
    }
	.u-search-box {
		padding: 18rpx 30rpx;
	}

	.u-menu-wrap {
		flex: 1;
		display: flex;
		overflow: hidden;
	}

	.u-search-inner {
		background-color: rgb(234, 234, 234);
		border-radius: 100rpx;
		display: flex;
		position: sticky;
		align-items: center;
		padding: 5rpx 16rpx;
		z-index: 9999;
	}

	.u-search-text {
		font-size: 26rpx;
		color: $u-tips-color;
		margin-left: 10rpx;
	}

	.u-tab-view {
		width: 200rpx;
		height: 100%;
	}

	.u-tab-item {
		height: 110rpx;
		background: #f6f6f6;
		box-sizing: border-box;
		display: flex;
		align-items: center;
		justify-content: center;
		font-size: 26rpx;
		color: #444;
		font-weight: 400;
		line-height: 1;
	}

	.u-tab-item-active {
		position: relative;
		color: #000;
		font-size: 30rpx;
		font-weight: 600;
		background: #fff;
	}

	.u-tab-item-active::before {
		content: "";
		position: absolute;
		border-left: 4px solid #ff9900;
		height: 32rpx;
		left: 0;
		top: 39rpx;
	}

	.u-tab-view {
		height: 100%;
	}

	.right-box {
		background-color: rgb(250, 250, 250);
	}

	.page-view {
		padding: 16rpx;
	}

	.class-item {
		margin-bottom: 30rpx;
		background-color: #fff;
		padding: 16rpx;
		border-radius: 8rpx;
	}

	.class-item:last-child {
		min-height: 100%;
	}

	.item-title {
		font-size: 26rpx;
		color: $u-main-color;
		font-weight: bold;
	}

	.item-menu-name {
		font-weight: normal;
		font-size: 24rpx;
		color: $u-main-color;
	}

	.item-container {
		display: flex;
		flex-wrap: wrap;
	}

	.thumb-box {
		width: 33.333333%;
		display: flex;
		align-items: center;
		justify-content: center;
		flex-direction: column;
		margin-top: 20rpx;
	}

	.item-menu-image {
		width: 120rpx;
		height: 120rpx;
	}
	.u-body-item {
			font-size: 32rpx;
			color: #333;
			padding: 5rpx 1rpx;
		}
			
		.u-body-item image {
			width: 200rpx;
			flex: 0 0 200rpx;
			height: 200rpx;
			border-radius: 8rpx;
			margin-bottom: 30rpx;
		}
	.title {
		position: absolute !important;
		margin-left: 200rpx;
		height: 200rpx;
		width: 300rpx;
		line-height: 50rpx;
		font-weight: 550;
		background: #fff;
		color: #333;
	}	
	.price {
		position: absolute !important;
		margin-left: 200rpx;
        margin-top: 90rpx;
		color: red;
		font-size: 28rpx;
	}
	.sales {
		position: absolute !important;
		height: 90rpx;
		right: 30rpx;
		text-align:right ;
		color: #333;
		font-size: 25rpx;
		
	}

</style>
